Hurricane Rosa heading towards Baja California peninsula and will bring excessive rainfall into deserts of SW United States

A weakening, but still strong hurricane Rosa is approaching Baja California peninsula where it is expected to make landfall tomorrow morning, Oct 1st local time. Rosa was a powerful CAT 4 hurricane earlier this week and is gradually weakening while moving over cooler waters near Mexico. Potentially dangerous and a rare occurrence for such a system, is its future path which leads Rosa across Arizona’s deserts. Torrential rainfall there usually results in dangerous flash floods and debris flows. Hurricane Rosa now has a central pressure of 984 mbar and sustained winds of 85 mph.

Water vapour satellite image of Rosa reveals a large hurricane with nicely visible upper-level outflow ventilation across its NE/NW quadrants.

The future track of Rosa pushes it across the northern parts of Baja California peninsula where Rosa weakens significantly and transforms into a tropical depression while moving across Arizona on Tuesday. It will bring enhanced threat for damaging flash floods.

Rosa is expected to continue weakening prior to landfall as much cooler waters are present along its path near the coast of Baja Calidornia peninsula as well as strengthening wind shear.

The main threat expected from the tropical depression / post-tropical storm Rosa or its remnants is excessive and torential rainfall in Baja California, northwestern Sonora and the deserts of southwest United States. High rainfall sums are expected to produce life-threatening flash flooding and debris flows in the deserts, and landslides in mountainous terrain.

Two more hurricanes will be ongoing across the eastern Pacific this week – we will have updates on those shortly.